Angle Adjustment Discontinuities for Golf Clubs

ABSTRACT

A golf club having a golf club shaft and a golf club head is provided. The shaft includes a proximal end, a distal end, and a longitudinal axis extending therebetween. The golf club head, which is attached to the distal end of the golf club shaft, extends from a heel region to a toe region. The golf club head includes an angle adjustment discontinuity that is located below the distal end of the golf club shaft. The angle adjustment discontinuity includes a first elongated groove extending over both a transverse distance and a longitudinal distance. The first elongated groove does not encircle the longitudinal axis.

FIELD OF THE INVENTION

This invention relates generally to golf clubs and golf club heads. More particularly, aspects of this invention relate to golf clubs having angle adjustment discontinuities.

BACKGROUND

Golf is enjoyed by a wide variety of players—players of different genders and dramatically different ages and/or skill levels. Golfers at all skill levels seek to improve their performance, lower their golf scores, and reach that next performance “level.” One way to improve performance is to use more technologically advanced equipment. A further way to improve performance is to select equipment that matches an individual golfer's style.

Golf clubs have been the subject of much technological research and advancement in recent years. Certain technological advancements have been made in an effort to better match the various elements and/or characteristics of the golf club and characteristics of a golf ball to a particular user's swing characteristics (e.g., club fitting technology, ball launch angle measurement technology, ball spin rates, etc.). There now exists a vast array of golf club component parts available to the golfer. For example, individual club head models may include variations in the loft angle, lie angle, offset features, weighting characteristics, etc. These various club heads may be combined with a variety of shafts having, for example, any of various stiffnesses, flex points, kick points or other flexion characteristics. Between the available variations in shafts and club heads, there are literally hundreds of different club head/shaft combinations available to the golfer.

Club fitters and golf professionals can assist in fitting golfers with a golf club head/shaft combination that suits their swing characteristics and needs. Not only should the individual golf head and shaft be selected based on the specific golfer's swing characteristics, but the angle at which the shaft is fitted to the head, i.e. the lie angle, should also be matched to the individual golfer's physical characteristics.

The lie angle is the angle between the center line of the hosel and the sole of the club head when the sole is touching the ground at the center of the face scoring area. If the center of the face scoring area of the club head is on the ground when a golfer stands at address then the lie of the club is generally considered perfect—this is termed a “standard” lie. If the toe of the club head points in the air and the heel of the club head is on the ground, then the golfer's lie is too “upright” and should be made flatter. In contrast, if the heel of the club head is in the air and the toe is on the ground, then the golfer's lie is too “flat” and should be made more upright. Shorter players generally use a flatter lie angle; taller players generally use a more upright lie angle.

The lie of the club can have a significant impact on ball flight. If the lie is too flat for a particular golfer, the toe of the club head may impact the ground first and the ball flight may tend to move from the inside outward. If the lie of the club is too upright for the golfer, the ball flight may tend to move from the outside inward.

Conventionally, shafts are mounted to golf club heads using hosels. In some instances, custom-fitting of golf clubs to an individual golfer has involved bending the hosel to provide the correct lie angle for that golfer/club combination.

However, the hosel, which is a structural connection between the shaft and the club head, may have material properties that are not amenable to bending. Thus, for example, wrinkles, bulges, stress concentrations, cracks, or other defects may result from the application of the bending forces. Further, bending may result in an attendant loss of strength and/or stiffness.

The disadvantages associated with conventional structures associated with adjusting a club's lie angle may limit the amount of adjustment and/or reduce the technical performance of the golf club.

SUMMARY

The following presents a general summary of aspects of the disclosure in order to provide a basic understanding of the invention and various features of it. This summary is not intended to limit the scope of the invention in any way, but it simply provides a general overview and context for the more detailed description that follows.

In accordance with illustrative aspects of the disclosure, a golf club head may include an angle adjustment discontinuity that is located below a distal end of an attached golf club shaft. The angle adjustment discontinuity may include a first elongated groove extending over both a transverse distance and a longitudinal distance. According to certain aspects, the first elongated groove does not encircle the longitudinal axis.

In accordance with other illustrative aspects of the disclosure, the angle adjustment discontinuity may include a first elongated groove extending over both a transverse distance and a longitudinal distance and a second elongated groove extending over both a transverse distance and a longitudinal distance.

In accordance with additional illustrative aspects of the disclosure, a golf club may include a golf club shaft attached to a golf club head as provided above.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and certain advantages thereof may be acquired by referring to the following detailed description in consideration with the accompanying drawings, in which:

FIG. 1 generally illustrates a front view of a portion of an example golf club according to an aspect of this disclosure;

FIG. 2 generally illustrates a heel-side view of a portion of an example golf club head in accordance with this disclosure and the aspect of FIG. 1;

FIG. 3 generally illustrates a back view of a portion of an example golf club head in accordance with this disclosure and the aspect of FIG. 1;

FIG. 4 generally illustrates a cross-section view taken through section IV-IV of FIG. 2 in accordance with this disclosure and the aspect of FIG. 1;

FIG. 4A generally illustrates an enlarged portion of FIG. 4, taken at section A-A club in accordance with this disclosure and the aspect of FIG. 1;

FIG. 5 generally illustrates a cross-section view taken through section IV-IV of FIG. 2 in accordance with this disclosure and an alternative embodiment of the aspect of FIG. 1;

FIG. 6 generally illustrates a heel-side view of a portion of an example golf club head according to another aspect of this disclosure;

FIG. 7 generally illustrates a heel-side view of a portion of an example golf club head according to a further aspect of this disclosure;

FIG. 8 generally illustrates a heel-side view of a portion of an example golf club head according to still another aspect of this disclosure;

FIG. 9 generally illustrates a heel-side view of a portion of an example golf club head according to an aspect of this disclosure; and

FIG. 10 generally illustrates a heel-side view of a portion of an example golf club head according to yet another aspect of this disclosure.

The reader is advised that the attached drawings are not necessarily drawn to scale and that certain features may have been exaggerated in or removed from the drawings for purposes of discussion.

DETAILED DESCRIPTION

In the following description of various example structures in accordance with the disclosure, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration various example connection assemblies, golf club heads, and golf club structures in accordance with the disclosure. Additionally, it is to be understood that other specific arrangements of parts and structures may be utilized and structural and functional modifications may be made without departing from the scope of the present invention. Also, while the terms “top,” “bottom,” “front,” “back,” “rear,” “side,” “underside,” “overhead,” and the like may be used in this specification to describe various example features and elements of the disclosure, these terms are used herein as a matter of convenience, e.g., based on the example orientations shown in the figures and/or the orientations in typical use. Nothing in this specification should be construed as requiring a specific three dimensional or spatial orientation of structures in order to fall within the scope of this invention.

A. General Description of Golf Club Angle Adjustment Discontinuities and Golf Clubs Including Such Features According to Examples of the Disclosure

In general, as described above, aspects of this disclosure relate to features for adjusting the lie and/or loft angles of golf clubs so that the club heads and shafts can be oriented at various angles with respect to one another. More detailed descriptions of aspects of this disclosure follow.

Illustrative aspects of this disclosure relate to features provided on golf club heads so that any of various lie and/or loft angles of a golf club shaft with respect to the club head body (and its ball striking face) can be readily achieved. The angle of a golf club shaft may be adjusted with respect to a golf club head body by deforming a portion of the club head. Generally, the deformation occurs as a result of bending stresses experienced in a bend region or at a bendline located between the distal end of the golf club shaft and body of the golf club head. Aspects of this disclosure relate to reducing stresses, strains and/or deformations in the bend region, that arise due to the angle of a club shaft to a club head being changed, by providing a means for relieving strains and/or stresses. A means for relieving these strains may include providing an angle adjustment discontinuity on the surface of the club head. An angle adjustment discontinuity may include one or more groove-like, crack-like, notch-like or other gap-forming elements that locally disrupt the continuity of the surface of the golf club head. The angle adjustment discontinuity may relieve or ameliorate strains in the bend region in both the longitudinal and the transverse directions. Further, the angle adjustment discontinuity may relieve stress concentrations and reduce the likelihood that wrinkles and or cracks may develop in the bend region.

1. Example Angle Adjustment Discontinuities and Golf Club Structures

A golf club having a golf club shaft and a golf club head is provided. The shaft includes a proximal end, a distal end, and a longitudinal axis extending therebetween. The golf club head, which is attached to the distal end of the golf club shaft, extends from a heel region to a toe region. The golf club head may include an angle adjustment discontinuity that is located below the distal end of the golf club shaft. The angle adjustment discontinuity may include a first elongated groove extending over both a transverse distance and a longitudinal distance. The first elongated groove does not encircle the longitudinal axis. In some aspects, the first groove does not extend more than 180 degrees around the longitudinal axis.

The angle adjustment discontinuity provides grooves extending over both transverse and longitudinal directions, with respect to the longitudinal axis defined by the golf club shaft. When the angle between the shaft and the club head body is adjusted, bending occurs in a bend region below the distal end of the shaft in the neck and/or heel region of the club head. On one side of the bend region, the material of the club head is stretched (or placed in tension) and on the other side of the bend region, the material of the club head is squashed (or place in compression). When a material is compressed in a first direction, it tends to want to expand in a direction perpendicular to the first direction. Similarly, when a material is stretched in a first direction, it tends to want to shrink in a direction perpendicular to the first direction. Thus, biaxial stresses and strains are developed in the bend region when the lie and/or loft angles are adjusted. By providing an angle adjustment discontinuity having one or more grooves extending in both the longitudinal and transverse directions, these biaxial stresses and strains may be better accommodated than grooves extending only in the transverse direction, for example.

According to aspects of this disclosure, a second elongated groove may also be provided. The second elongated groove may extend over both a transverse distance and a longitudinal distance. Further, the second elongated groove does not encircle the longitudinal axis. The first and second grooves may be formed as a series of concentric circles. More generally, the first groove and/or the second groove may form closed loops that extend substantially parallel to one another. The angle adjustment discontinuity may include more than two grooves.

The angle adjustment discontinuity may be provided at least partially in a neck region of the club head. Optionally, the angle adjustment discontinuity may be provided at least partially in a heel region of the club head. In some aspects, the angle adjustment discontinuity may be symmetric with respect to an axis parallel to the longitudinal axis. In other aspects, the angle adjustment discontinuity may be symmetric with respect to an axis perpendicular to the longitudinal axis.

While the angle adjustment discontinuity provides relief for the biaxial bending stresses and strains developed during bending, it does so with the removal a very little material from the cross-section of the neck and/or heel region. Thus, the properties of the club head that affect the bending and rotational stiffness of the club (i.e., the moment of inertia and the center of gravity) are only minimally affected.

According to certain aspects of this disclosure a golf club includes a golf club shaft having a proximal end, a distal end, and a longitudinal axis defining a longitudinal direction extending therebetween. The golf club head is attached to the distal end of the golf club shaft. The head includes a means for relieving strain located below the distal end of the golf club shaft. The means for relieving strain including a first elongated gap-forming element extending over both a transverse distance and a longitudinal distance. The first elongated gap-forming element does not encircling the longitudinal axis.

According to other aspects of this disclosure a golf club includes a golf club shaft having a proximal end, a distal end, and a longitudinal axis defining a longitudinal direction extending therebetween. The golf club further includes a golf club head attached to the distal end of the golf club shaft. The golf club head includes an angle adjustment discontinuity located below the distal end of the golf club shaft. The angle adjustment discontinuity may include a first elongated groove extending over both a transverse distance and a longitudinal distance and a second elongated groove also extending over both a transverse distance and a longitudinal distance.

The first and second grooves may have a synergistic effect. For example, each groove may relieve a portion of the biaxial bending stresses and strains. Further, multiple grooves may provide a more distributed relief feature. Even further, the multiple grooves may better accommodate potential variations in the orientation of the angle being adjusted. Unsightly wrinkles or other undesirable deformations at the bend region may be avoided.

The angle adjustment discontinuities described herein can help keep the overall connection assembly relatively compact and lightweight, while facilitating lie and loft angle adjustment and maintaining rotational and bending stiffness.

Aspects of this disclosure relating to the angle adjustment discontinuities and to golf club structures that incorporate the angle adjustment discontinuities will be described in more detail below.

Specific examples of the disclosure are described in more detail below. The reader should understand that these specific examples are set forth merely to illustrate examples of the disclosure, and they should not be construed as limiting the disclosure.

B. Specific Examples of the Disclosure

FIGS. 1-3 generally illustrate example golf clubs 100 in accordance with at least certain aspects of this disclosure. FIGS. 4-9 generally illustrate various embodiments of angle adjustment discontinuities according to aspects of this disclosure.

Referring to FIG. 1, the club 100 includes a club head 102 and a club shaft 106. The club shaft 106 has a proximal end where a golfer grips the shaft (not shown), a distal end where the club head 102 is attached to shaft 106, and a longitudinal axis (L) extending along the length of the shaft from the proximal to the distal end.

As shown in FIG. 1, the club head 102 includes a main body 120, a neck 130 and a club head-to-shaft connection region 140. The club head 102 may be attached to the distal end of the club shaft 106 at the club head-to-shaft connection region 140. The club head-to-shaft connection region 140 may be provided by a hosel 142. The club head-to-shaft connection region 140 may be defined as the region where the shaft 106 and the club head 102 overlap. In certain embodiments, the club head-to-shaft connection region 140 is that region where the distal end of the club shaft 106 and the hosel 142 overlap.

The club head 102 includes a main body 120 that extends from a heel region 122 to a toe region 124. A ball-striking face member 126 may be provided on the front face of the main body 120. Neck region 130 extends between the main body 120 and the club head-to-shaft connection region 140. The neck region 130 generally includes an elongated structure that extends generally in the same direction as the longitudinal axis L of the club shaft 106. The main body 120 extends from the neck region 130 in a direction that is generally transverse to the direction of extension of the neck region 130. However, it is recognized that the demarcation between the heel region 122 of the main body 120 and the neck region 130 may not be clearly defined. Thus, a transition region 132 is defined where the neck region 130 and the heel region 122 merge. Transition region 132 may include portions of both the neck region 130 and the heel region 122.

An angle adjustment discontinuity 150 is provided on the club head 102. The angle adjustment discontinuity 150 is located below the club head-to-shaft connection region 140. In other words, the angle adjustment discontinuity 150 is located distally beyond the distal end of the golf club shaft. In certain aspects, the angle adjustment discontinuity 150 may be located in the neck region 130. In other aspects, the angle adjustment discontinuity 150 may be located in the transition region 132. In even other aspects, the angle adjustment discontinuity 150 may be located in the heel region 122.

The angle adjustment discontinuity 150 facilitates the adjustment of the angle (lie and/or loft) of the club shaft 106 relative to the club head 102. This angle of the club shaft 106 relative to the club head 102 may be adjusted by deforming (e.g., bending) the club head 102 at a bend line 125. The bend line 125 is located below the head-to-shaft connection region 140 and may be located in the neck region 130, the heel region 122, or the transition region 132. According to certain aspects, the angle adjustment discontinuity 150 may reduce bending stresses and reduce or eliminate undesirable deformations when the angle of the club shaft 106 is changed. According to other aspects, the angle adjustment discontinuity 150 may assist in defining the location of the bend line 125.

A range of desired angle adjustments may be accommodated without departing from this disclosure. By way of non-limiting example, adjustments of at least 0.25 degrees, at least 0.5 degrees, at least 1 degree, at least 2 degrees, at least 4 degrees, or even at least 8 degrees may be accommodated by the angle adjustment discontinuity. In some example structures, the desired adjustment will be between 0.25 and 25 degrees, between 0.5 and 15 degrees, between 1 and 10 degrees, or even between 1 and 5 degrees.

The angle adjustment discontinuity 150 in accordance with some aspects of this disclosure will now be described in more detail with reference to FIGS. 2 and 4 through 10.

As shown in FIG. 2, the angle adjustment discontinuity 150 includes a plurality of grooves 152 located in the transition region 132. A groove is a relatively long, narrow channel, i.e. a groove has a length that is elongated compared to its width. According to certain aspects, a groove may be defined as having a length-to-width ratio of 5 or more. More typically, a groove may have a length-to-width ratio of 10 or more, or 15 or more, or even 20 or more.

In FIG. 2 a series of three concentric, circular grooves 152 a-152 c are illustrated. Each of these grooves 152 extends in at least two dimensions: over a transverse distance and over a longitudinal distance. A transverse distance is measured perpendicular to the longitudinal axis L of the club shaft 106. A longitudinal distance is measured in a direction that is aligned with the longitudinal axis L of the club shaft 106. In other words, the grooves 152 do not lie in a plane that is perpendicular to the longitudinal axis L of the club shaft 106. For example, referring to FIG. 2, the outermost groove 152 c extends over a transverse distance DT and a longitudinal distance DL.

In the embodiment shown in FIGS. 1-3, the grooves 152 form closed loops.

However, these grooves are not circumferential grooves, i.e., the closed loops of the grooves 152 do not encircle the longitudinal axis L. Rather, the closed loops of the grooves 152 encircle an axis that is extends at an angle to the longitudinal axis. The groove 152 b extends around groove 152 a; groove 152 c extends around both groove 152 b and groove 152 a. Further, the grooves 152 a-152 c extend substantially parallel to each other, when viewed perpendicular to the surface of the transition region 132. For purposes of this disclosure, a person of ordinary skill in the art would recognize when grooves are substantially parallel. By way of non-limiting example, grooves that deviate from the parallel by 5 or even 10 degrees would be considered substantially parallel.

In general, when the angle of the longitudinal axis L of the club shaft 106 is adjusted relative to the main body 120, the material at the bendline 125 undergoes permanent deformation. The grooves 152 may provide a strain relief feature, in that the sides of the groove channels 154 may be deformed toward or away from one another when the club shaft angle is adjusted. With a groove 152 extending in both a transverse and a longitudinal direction on the surface of the club head 102, strain relief in both the transverse and the longitudinal directions may be provided. The grooves 152 may be formed by any conventional method, including for example by casting, forging, molding, machining, etching, incising, scoring etc.

The cross-sectional shape of the groove channels 154 may be substantially rectangular, rounded, triangular, or any other suitable shape. For example, in FIGS. 4 and 4A, grooves 152 a-152 c have groove channels 154 a-154 c with substantially triangular cross sections. The depth of the groove channel (d) may range from 0.1 mm to 5 mm. A depth greater than 0.5 mm, or greater than 1 mm, or even greater than 1.5 mm may be most desirable. Further, the width of the groove channels as measured at the surface (w) may range from 0.1 mm to 5 mm. A width of greater than 0.5 mm, or greater than 1 mm, or even greater than 1.5 mm may be most desirable.

In general, the groove channels may range from very shallow to very deep. Thus, for example, groove channels may have a width-to-depth ratio of 0.5, or 0.2 or even 0.1 or less for grooves that are considered to be deep. For shallow grooves, the width-to-depth ratio of 1.5 or more may be suitable, including for example ratios of 2, or 5, or even of 10 or greater. This width-to-depth ratio need not be constant for any given groove.

As shown in FIG. 4A, the depth dimensions (d) of the groove channels 154 a-154 c are oriented substantially perpendicular to the surface (S). Slight deviations from the perpendicular, for example, by 5, 10, or even 15 degrees, would still be considered substantially perpendicular. Further, the depths of the groove channels 154 a-154 c for each of the grooves 152 a-152 c are substantially equal. FIG. 5 illustrates an alternative embodiment for grooves 152 a-152 c of FIGS. 1-3. In this alternative embodiment, grooves 152 a′-154 c′ have groove channels 154 a′-154 c′ with substantially rectangular cross sections. The depth dimensions of the groove channels 154 a′-154 c′ are oriented parallel to one another. Further, the depths d_(a), d_(b), d_(c) of the groove channels 154 a′-154 c′ vary for the different grooves.

Thus it can be seen that the plurality of grooves 152 need not have the same cross-sectional shape or dimensions. By way of non-limiting example, a first groove may have a depth (and/or a width) that is different than the depth (and/or width) of a second groove. Further, each individual groove need not have the same cross-sectional shape or dimension along its length. Thus, by way of other non-limiting examples, the depth of any one groove may vary along the length of the groove and/or the width of any one groove may vary along the length of the groove. Further, the plurality of grooves 152 need not be equally spaced from each other.

Referring back to FIG. 4, an angle α defines the extent to which the angle adjustment discontinuity 150 extends around the longitudinal axis L. In this particular embodiment, the angle α also defines the extent to which the groove 152 c extends around the longitudinal axis L.

FIG. 6 illustrates aspects of the disclosure wherein the adjustment feature includes two grooves 152 d and 152 e, each extending in both a transverse and a longitudinal direction on the surface of the club head 102 in the transition region 132. These grooves are generally elliptical in shape. Further, these grooves are shown being substantially parallel to each other, when view from a perpendicular to the surface in the transition region 132. Even further, grooves 152 d and 152 e are substantially positioned with respect to a common center.

FIG. 7 illustrates other aspects of the disclosure wherein the adjustment feature 150 includes three grooves 152 f, 152 g and 152 h, each extending in both a transverse and a longitudinal direction on the surface of the club head 102 in the transition region 132. Groove 152 f is rectangular; groove 152 g is elliptical; and groove 152 h is circular. Grooves 152 f-152 h have a common center.

FIG. 8 illustrates even other aspects of the disclosure wherein the adjustment feature 150 includes six grooves 152 i-152 n, each extending in both a transverse and a longitudinal direction on the surface of the club head 102 in the transition region 132. Grooves 152 i and 152 j are segments of a circle of a first radius, with the segments placed in mirror-image opposition to one another. Grooves 152 k and 152 n are segments of a circle of a second radius, equally spaced on a circle of the second radius. Thus, it can be seen that groove 152 k extends substantially in the longitudinal direction, but also extends in the transverse direction and that groove 152 l extends substantially in the transverse direction, but also extends in the longitudinal direction. FIG. 9 illustrates certain other aspects of the disclosure wherein the adjustment feature 150 includes a single, circular, spiral groove 152 o extending in both a transverse and a longitudinal direction on the surface of the club head 102. The axis of the spiral is not aligned with the longitudinal axis L. Indeed, the axis of the spiral is substantially perpendicular to the longitudinal axis L. The number of windings of the spiral is not critical. Further, the windings need not be even spaced from the center of the spiral. Even further, the spiral need not be based on a circle, but could be based on an elliptical, square, rectangular, triangular, or other regular or irregular shapes.

FIG. 10 illustrates even other aspects of the disclosure wherein the adjustment feature 150 includes at least one chevron-like groove 152 p extending in both a transverse direction and a longitudinal direction on the surface of the club head 102. This particular groove embodiment further includes a second chevron-like groove 152 q. The points of the chevron-like grooves 152 p, 152 q are shown facing away from each other in the embodiment of FIG. 10. Alternatively, the points of the chevrons may face toward each other, may face in the same direction, or may face in any direction. The chevron-like grooves may have relatively low groove length-to-width ratios. The length (l) of the chevron-like groove may be taken as the sum of the length of each leg of the chevron; the width (w) of the chevron-like groove is, at its maximum, the dimension across the groove where the legs of the chevron meet. By way of non-limiting example, the groove length-to width ratio may range from approximately 3 to approximately 30.

Club head 102 may be formed as a unitary piece (i.e., a single piece) or assembled from multiple pieces. The various parts of the club heads 102 may be made from conventional materials, in conventional constructions, in conventional manners, as are known and used in the art, optionally modified (if necessary, e.g., in size, shape, etc.) to accommodate the lie angle adjustment discontinuities described herein. For example, one or more of the various parts comprising the club head 102 may be made from a metal material, including lightweight metals conventionally used in golf club head constructions, such as aluminum, titanium, magnesium, nickel, alloys of these materials, steel, stainless steel, and the like, optionally anodized finished materials. Alternatively, if desired, one or more of the various parts of the club head 102 may be made from rigid polymeric materials, such as polymeric materials conventionally known and used in the golf club industry. The various parts of the club head 102 may be made from the same or different materials without departing from this disclosure. The parts may be made in conventional manners as are known and used in the metal working and/or polymer production arts. Further, any desired materials also may be used for the shaft 106, including conventional materials that are known and used in the art, such as steel, graphite, polymers, composite materials, combinations of these materials, etc. Even further, the club head 102 may be attached to the club shaft 106 in any known manner using conventional fittings and materials. For example, the club head 102 may be permanently attached to the club shaft 106, via bonding, brazing, welding, cements, adhesives, etc., or the club head 102 may be releasably attached to the club shaft, via threads, mechanical fasteners, etc. Optionally, a grip member (not shown) may be provided at the proximal end of the shaft 106.

Many variations in the overall structure of the shaft, club head, and club head/shaft connection assembly are possible without departing from this disclosure. For example, more than one angle adjustment discontinuity may be provided on the club head. The first and second angle adjustment discontinuities may be located on opposite sides of the longitudinal axis. While an iron-type golf club head is illustrated in these figures, aspects of this disclosure may be applied to any type of club head, including, for example: fairway wood club heads; driver/wood-type golf club heads; hybrid golf club heads; putter heads; and the like.

Conclusion

While the disclosure has been described in detail in terms of specific examples including presently preferred modes of carrying out the disclosure, those skilled in the art will appreciate that there are numerous variations and permutations of the above described features and systems. Thus, the spirit and scope of the disclosure should be construed broadly as set forth in the appended claims. 

1. A golf club comprising: a golf club shaft having a proximal end, a distal end, and a longitudinal axis defining a longitudinal direction extending therebetween; and a golf club head attached to the distal end of the golf club shaft, the head including: an angle adjustment discontinuity located below the distal end of the golf club shaft, the angle adjustment discontinuity including a first elongated groove extending over both a transverse distance and a longitudinal distance, the first elongated groove not encircling the longitudinal axis.
 2. The golf club according to claim 1, wherein the first groove forms a closed loop.
 3. The golf club according to claim 1, further including a second elongated groove extending over both a transverse distance and a longitudinal distance, the second elongated groove not encircling the longitudinal axis.
 4. The golf club according to claim 3, wherein the second elongated groove extends substantially parallel to the first elongated groove.
 5. The golf club according to claim 1, wherein the angle adjustment discontinuity is symmetric with respect to an axis parallel to the longitudinal axis.
 6. The golf club according to claim 1, wherein the angle adjustment discontinuity is symmetric with respect to an axis perpendicular to the longitudinal axis.
 7. The golf club according to claim 1, wherein the first elongated groove does not extend more than 180 degrees around the longitudinal axis.
 8. The golf club according to claim 1, wherein the head includes a neck region and wherein the first elongated groove is located at least partially in the neck region.
 9. The golf club according to claim 1, wherein the head includes a heel region and wherein the first elongated groove is located at least partially in the heel region.
 10. The golf club according to claim 1, further including at least a third elongated groove.
 11. A golf club comprising: a golf club shaft having a proximal end, a distal end, and a longitudinal axis defining a longitudinal direction extending therebetween; and a golf club head attached to the distal end of the golf club shaft, the head including: a means for relieving strain located below the distal end of the golf club shaft, the means for relieving strain including a first elongated gap-forming element extending over both a transverse distance and a longitudinal distance, the first elongated gap-forming element not encircling the longitudinal axis.
 12. The golf club according to claim 11, wherein the second elongated gap-forming element extends substantially parallel to the first elongated gap-forming element.
 13. The golf club according to claim 11, wherein the first elongated gap-forming element forms a closed loop that does not encircle the longitudinal axis.
 14. The golf club according to claim 11, wherein the means for relieving strain is symmetric with respect to an axis parallel to the longitudinal axis.
 15. The golf club according to claim 11, wherein the means for relieving strain is symmetric with respect to an axis perpendicular to the longitudinal axis.
 16. The golf club according to claim 11, wherein the first elongated gap-forming element does not extend more than 180 degrees around the longitudinal axis.
 17. The golf club according to claim 11, wherein the head includes a neck region and wherein the first elongated gap-forming element is located at least partially in the neck region.
 18. The golf club according to claim 11, wherein the head includes a heel region and wherein the first elongated gap-forming element is located at least partially in the heel region.
 19. The golf club according to claim 11, further including at least a third elongated gap-forming element.
 20. A golf club head comprising: a main body extending from a heel region to a toe region; a neck region extending from the heel region to a connection region and defining a longitudinal axis, the connection region configured for attachment to a distal end of a golf club shaft; and an angle adjustment discontinuity located below the connection region, the angle adjustment discontinuity including a first elongated groove extending over both a transverse distance and a longitudinal distance, the first elongated groove not encircling the longitudinal axis.
 21. A golf club comprising: a golf club shaft having a proximal end, a distal end, and a longitudinal axis defining a longitudinal direction extending therebetween; and a golf club head attached to the distal end of the golf club shaft, the head including: an angle adjustment discontinuity located below the distal end of the golf club shaft, the angle adjustment discontinuity including a first elongated groove extending over both a transverse distance and a longitudinal distance and a second elongated groove extending over both a transverse distance and a longitudinal distance. 